The present invention relates to an injection product for the impermeabilization and/or consolidation of soils and building materials, such as mortars, binders, masonry, concretes etc., having more or less deep fissures or voids that might result in porosity and hence permeability.
The present invention relates also to a method of employing such an injection product for the purpose of improving the impermeability of and/or of consolidating such soils and building materials.
More particularly, the present invention is intended for the treatment of particularly fine or very fine materials and soils to modify their consistency.
For the sealing and/or consolidation of soils and materials it is current practice to use cement-base sealing and/or consolidating products still called "grouts" when the pores are more or less large, or silica gel type products obtained by jelling sodium silicate, when the pores are particularly fine.
This latter class of grouts, however, may cause the problem of polluting the soil, particularly at the level of the water tables, and also of poor durability since the structure of the gels obtained may not be lastingly stable. This phenomenon, known as "syneresis," can be very harmful to the gels obtained from silicate solutions.
To remedy the deficiencies of these injection grouts French patent No.83.09647 has proposed an injection grout particularly for micropores and microfissures, which is in the form of a noncolloidal silica liquor obtained by dissolving at ambient temperature silica having an average particle diameter less than 100 microns in soda, the ratio of SiO.sub.2 to Na.sub.2 O being less than 2 and the silica content of the solution being preferably greater than about 20% by weight.
This type of grout is highly reactive to calcium, which is present in building materials and certain soils, and therefore leads to a mineralization of soils and/or building materials by the formation of stable and insoluble hydrated calcium silicates, thus assuring the permanence of the treatment performed on these soils and materials.
These grouts present certain problems, however, due to the fact that the setting time has proven to be particularly sensitive to temperature conditions and to the concentrations of the various products present.
In certain applications it is particularly important to have grouts that have a constant and controllable setting time.
When the point of injection is remote from the place where the grout is prepared it is important to have grouts which have a variable but constant setting time, so as to assure good repeatability of the injection operations.
In French Patent No. 72.06150 it has been proposed, in order to vary the setting time, to replace a portion of the cement of an injection grout containing sodium silicate or an aqueous solution of sodium silicate and a cement paste, with a mineral substance having latent hydraulic properties, such as a finely granulated slag.
Although the addition of slag actually does affect the setting time, it is too fast, even with heavy concentrations of slag. Furthermore, this type of sodium silicate base grout already has, at time t=0, a high viscosity (&gt;15 cp) which does not allow it to be injected into very fine soils such as Fontainebleau sands.
The present invention permits the solution of the problems involved in known grouts and therefore it proposes a sealing and/or consolidation product for soils and building materials having a stable and controllable setting time and having furthermore an appropriate viscosity to permit good penetration into fine or very fine soils as well as in the fissures and microfissures in building materials.
Quite surprisingly and unexpectedly, it has been found that, in accordance with the invention, the addition of slag to the grout in accordance with French patent No. 83.09647 resulted in setting times of longer than about 1 hour, whereas the grout according to French patent No. 72.06150 had a setting time of several minutes or, in any case, less than one hour.
Such a difference in reactivity was quite unforeseeable inasmuch as it is well known that grouts based on silica liquor have a much greater reactivity than grouts based on sodium silicate.